﻿namespace MSHelpMe
{
    using System.IO;
    using System.IO.IsolatedStorage;
    using System.Threading;
    using System.Windows;
    using System.Windows.Navigation;
    using Microsoft.Phone.Controls;
    using Microsoft.Phone.Shell;
    using ViewModels;

    public partial class App
    {
        private const string StorageFileName = "state.xml";
        private const string StateKey = "state";

        private static MainViewModel viewModel;

        /// <summary>
        /// A static ViewModel used by the views to bind against.
        /// </summary>
        /// <returns>The MainViewModel object.</returns>
        public static MainViewModel ViewModel
        {
            get
            {
                // Delay creation of the view model until necessary
                return viewModel ?? (viewModel = new MainViewModel());
            }
        }

        /// <summary>
        /// Provides easy access to the root frame of the Phone Application.
        /// </summary>
        /// <returns>The root frame of the Phone Application.</returns>
        public PhoneApplicationFrame RootFrame { get; private set; }

        /// <summary>
        /// Constructor for the Application object.
        /// </summary>
        public App()
        {
            // Global handler for uncaught exceptions. 
            // Note that exceptions thrown by ApplicationBarItem.Click will not get caught here.
            UnhandledException += Application_UnhandledException;

            // Show graphics profiling information while debugging.
            if (System.Diagnostics.Debugger.IsAttached)
            {
                // Display the current frame rate counters.
                Current.Host.Settings.EnableFrameRateCounter = true;

                // Show the areas of the app that are being redrawn in each frame.
                //Application.Current.Host.Settings.EnableRedrawRegions = true;

                // Enable non-production analysis visualization mode, 
                // which shows areas of a page that are being GPU accelerated with a colored overlay.
                //Application.Current.Host.Settings.EnableCacheVisualization = true;
            }

            // Standard Silverlight initialization
            InitializeComponent();

            // Phone-specific initialization
            InitializePhoneApplication();
        }

        // Code to execute when the application is launching (eg, from Start)
        // This code will not execute when the application is reactivated
        private void Application_Launching(object sender, LaunchingEventArgs e)
        {
            var t = new Thread(() =>
                                   {
                                       var iso = IsolatedStorageFile.GetUserStoreForApplication();

                                       if (iso.FileExists(StorageFileName))
                                       {
                                           using (var reader = new StreamReader(iso.OpenFile(StorageFileName, FileMode.Open)))
                                           {
                                               ViewModel.LoadData(reader.ReadToEnd());
                                           }
                                       }
                                   });
            t.Start();
        }

        // Code to execute when the application is activated (brought to foreground)
        // This code will not execute when the application is first launched
        private void Application_Activated(object sender, ActivatedEventArgs e)
        {
            if (!e.IsApplicationInstancePreserved && PhoneApplicationService.Current.State.ContainsKey(StateKey))
            {
                // The application state was saved before, restore it.
                viewModel = PhoneApplicationService.Current.State[StateKey] as MainViewModel;
            }
        }

        // Code to execute when the application is deactivated (sent to background)
        // This code will not execute when the application is closing
        private void Application_Deactivated(object sender, DeactivatedEventArgs e)
        {
            PhoneApplicationService.Current.State[StateKey] = ViewModel;
            SaveDataToIsolatedStorage(StorageFileName, ViewModel);
        }

        // Code to execute when the application is closing (eg, user hit Back)
        // This code will not execute when the application is deactivated
        private void Application_Closing(object sender, ClosingEventArgs e)
        {
            SaveDataToIsolatedStorage(StorageFileName, ViewModel);
        }

        // Code to execute if a navigation fails
        private void RootFrame_NavigationFailed(object sender, NavigationFailedEventArgs e)
        {
            if (System.Diagnostics.Debugger.IsAttached)
            {
                // A navigation has failed; break into the debugger
                System.Diagnostics.Debugger.Break();
            }
        }

        // Code to execute on Unhandled Exceptions
        private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
        {
            if (System.Diagnostics.Debugger.IsAttached)
            {
                // An unhandled exception has occurred; break into the debugger
                System.Diagnostics.Debugger.Break();
            }
        }

        private void SaveDataToIsolatedStorage(string fileName, MainViewModel state)
        {
            var iso = IsolatedStorageFile.GetUserStoreForApplication();

            using(var writer = new StreamWriter(iso.OpenFile(fileName, FileMode.Create)))
            {
                writer.WriteLine(state.ToXml());
            }
        }

        #region Phone application initialization

        // Avoid double-initialization
        private bool phoneApplicationInitialized;

        // Do not add any additional code to this method
        private void InitializePhoneApplication()
        {
            if (phoneApplicationInitialized)
                return;

            // Create the frame but don't set it as RootVisual yet; this allows the splash
            // screen to remain active until the application is ready to render.
            RootFrame = new PhoneApplicationFrame();
            RootFrame.Navigated += CompleteInitializePhoneApplication;

            // Handle navigation failures
            RootFrame.NavigationFailed += RootFrame_NavigationFailed;

            // Ensure we don't initialize again
            phoneApplicationInitialized = true;
        }

        // Do not add any additional code to this method
        private void CompleteInitializePhoneApplication(object sender, NavigationEventArgs e)
        {
            // Set the root visual to allow the application to render
// ReSharper disable RedundantCheckBeforeAssignment
            if (RootVisual != RootFrame)
// ReSharper restore RedundantCheckBeforeAssignment
            {
                RootVisual = RootFrame;
            }

            // Remove this handler since it is no longer needed
            RootFrame.Navigated -= CompleteInitializePhoneApplication;
        }

        #endregion
    }
}